In electrosurgery a radiofrequency generator is adapted to be connected to a handheld or robotically held probe or electrode which the surgeon brings into contact with tissue. Depending upon the frequency of the generated current, the electrode may either cauterize the tissue or, at a higher frequency, cut the tissue.
When the electrode tip is accidentally brought into contact with body tissue on the patient or the surgeon, the tissue may be punctured or otherwise damaged in a potentially serious manner.
It has been proposed to provide an electrosurgical electrode with an insulating housing that allows the tip to be retracted within the housing to prevent accidental damage by contact with the tip. For example, in U.S. Pat. No. 6,569,161, springs within the device apparently urge the tip into an extended position with respect to the housing. After use the electrode is retracted back into the housing by pressing the tip of the electrode against a surface to cause a needle to retract back into the housing. It is apparently locked into this retracted position until released by a switch 24. Accordingly, the normal position, or default position, of the device is with the electrode extended and it may be retracted into the housing by forcing the extending spring into a retracted position. This design appears to be inherently unsafe in that the failure of the trigger mechanism will allow the electrode to be extended into its potentially dangerous position.